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STAT 200 QUIZ 3

 

There are 23 problems. Mark only ONE choice in each problem.

01:  An assumption made about the value of a population parameter is called a

  1. conclusion
    B. confidence
    C. significance
  2. hypothesis
  3. none of the above

02:  The p-value is a probability that measures the support or lack of support for the

  1. null hypothesis
  2. alternative hypothesis
    C. either the null or the alternative hypothesis
    D. sample statistic
    E. none of the above

03:  In a t-test, which of the following does not need to be known in order to compute the p-value?

  1. knowing whether the test is one-tail or two-tails
  2. the value of the test statistic
    C. the level of significance
          D. the Degrees of Freedom
    E. none of the above

04:  As the test statistic becomes larger, the p-value
A. becomes smaller
      B. becomes larger
C. becomes negative
D. stays the same because the sample size has not been changed
E. none of the above

05:  What type of error occurs if you fail to reject H0 when, in fact, it is not true?

  1. Type I
          B. Type II
    C. Either Type I or Type II, depending on the level of significance.
    D. Either Type I or Type II, depending on whether the test is one tailed or two tailed.
    E. None of the above.

06:  The level of significance α is the
A. same as the p-value
B. 1 – β
C. maximum allowable probability of Type II error
D. maximum allowable probability of Type I error
      E. none of the above

07:  In hypotheses testing if the null hypothesis has been rejected when the alternative hypothesis is   true, then
A. a Type I error has been committed

  1. a Type II error has been committed
  2. either a Type I or Type II error has been committed
    D. the correct decision has been made
  3. none of the above

08:  In a one-tail, left-tail z-test, the test statistic is z = -2.01.  The p-value is
A. 0.0179
B. 0.0228
C. 0.0222
D. 0.0174
E. none of the above

09:  In a two-tail z-test, the test statistic is z = -2.5. The p-value for this test is
A. -1.25
B. 0.4938
C. 0.0062
D. 0.0124
E. none of the above

10:  In a two-tail t-test, the test statistic t = -2.89 and the sample size is 30. The p-value is
A. 0.9928
B. 0.0019
C. 0.0038
D. 0.0036
E. 0.0072

  1. In one-tail, left-tailt-test, the test statistic t = -1.58 and the sample size is 23. The p-value is
  2. 0.0571
  3. 0.9358
  4. 0.0642
  5. 0.1284
  6. 0.0639

12:  The average life expectancy of a certain brand of tire has been 40,000 miles. Because of a new       manufacturing process introduced it is believed that the life expectancy has increased. To test the       validity of this the correct set of hypotheses is
A. H0: µ < 40,000       HA: µ ≥ 40,000
B. H0: µ = 40,000        HA: µ ≥ 40,000
C. H0: µ > 40,000        HA: µ ≤ 40,000
D. H0: µ = 40,000       HA: µ < 40,000
E. H0: µ = 40,000        HA: µ > 40,000

13:  What kind of Alternative Hypothesis is used in the figure below?

  1. HA: µ = µ0
    B. HA: µ ≠ µ0
    C. HA: µ > µ0
    D. HA: µ < µ0
    E. none of the above
  2. Which type of Alternative Hypothesis is used in the figure below?
  3. HA: µ = µ0
    B. HA: µ ≠ µ0
    C. HA: µ > µ0
    D. HA: µ < µ0
    E. none of the above

15:  A soft drink filling machine, when in perfect adjustment, fills the bottles with 12 ounces of soft drink. If the machine overfills or under fills then it must be shut down and readjusted.  To   determine whether or not the machine is properly adjusted, the correct set of hypotheses is

  1. H0: µ < 12              HA: µ ≥ 12
  2. H0: µ = 12               HA: µ > 12
  3. H0: µ ≠ 12               HA: µ = 12
  4. H0: µ = 12              HA: µ ≠ 12
  5. H0: µ = 12               HA: µ < 12

Use the following information to do the next four problems.

A random sample of 100 people was taken. In the sample 85% favored Candidate Green. We are interested in determining whether or not the proportion of the population in favor of Green is significantly more than 80%.

16:  The correct set of hypotheses for this problem is

  1.  H0: = 0.85 and HA> 0.85
          B. H0: p > 0.80 and HA: p = 0.80
    C. H0: = 0.80 and HAp > 0.80
          D. H0: = 0.80 and HA 0.80
    E. H0:  0.80 and HAp > 0.80

17:  Find the test statistic.

  1. 0.80
  2. 0.05
  3. 1.25
  4. 2.00
  5. none of the above

18:  Find the p-value.

  1. 0.1071
  2. 0.8929
  3. 0.8944
  4. 0.1056
    E. none of the above

19:  At the 5% level of significance, can we conclude that the proportion of the population in favor    of Green

  1. is significantly greater than 80%
  2. is not significantly greater than 80%
  3. is significantly greater than 85%
  4. is not significantly greater than 85%
  5. none of the above

Use the following information to do the next four problems.

The sales of a grocery store had an average of $8,000 per day. The store started an aggressive advertizing campaign in order to increase sales. To determine whether or not the advertizing campaign has been effective, i.e. the sales increased, a sample of 66 days was selected. For this sample the mean was $8,300 per day and the standard deviation $1,200.

20:  The correct Alternative Hypothesis for this problem is

  1. HA:   x‾ > 8,000
  2.  HA:   x‾ ≥ 8,000
  3.  HA:   µ > 8,300
  4.  HA:   µ ≥ 8,000
  5.  HA:   none of the above

21:  The value of the test statistic is

  1. -2.03
  2.   2.03
  3. -2.00
  4.   2.00
  5. none of the above

22:  The p-value is

  1. 0.0248
  2. 0.0228
  3. 0.9752
  4. 0.9768
  5. 0.0232

23:  At the 5% level of significance, can we conclude that the advertizing campaign

  1. increased sales?
  2. decreased sales?
  3. did not much affect sales?
  4. was not worth the cost?
  5. none of the above